The Trace Minerals

1. The Trace Minerals Chapter 13

2. The Trace Minerals – An Overview • Food sources • Depend on soil and water composition • Depend on food processing • Deficiencies • Can affect people of all ages • May be difficult to recognize • Toxicities • FDA regulation of supplements

3. The Trace Minerals – An Overview • Interactions • Common and well coordinated • May lead to nutrient imbalances • Cause a deficiency • Interfere with work of minerals • Contaminant minerals causing toxic reactions

4. Iron • Too little and too much can be harmful • Roles in the body • Switches back and forth between two forms • Ferrous iron • Ferric iron • Cofactor in oxidation-reduction reactions • Part of electron carriers • Hemoglobin and myoglobin

5. Iron • Absorption • Body conserves iron • Balance maintained primarily through absorption • Ferritin • Iron-storage in small intestine • Transferrin • Iron transport protein

6. Iron Absorption

7. Iron in food If the body does not need iron Iron is not absorbed and is excreted in shed intestinal cells instead. Thus, iron absorption is reduced when the body does not need iron. Mucosal cells in the intestine store excess iron in mucosal ferritin (a storage protein). If the body needs iron Mucosal ferritin releases iron to mucosal transferrin (a transport protein), which hands off iron to another transferrin that travels through the blood to the rest of the body. Stepped Art Fig. 13-2, p. 426

8. Iron • Absorption • Dietary sources • Heme iron • Nonheme iron • Absorption-enhancing factors • MFP • Vitamin C • Some acids and sugars

9. Heme and Nonheme Iron in Foods

10. Only foods derived from animal flesh provide heme, but they also contain nonheme iron. Heme accounts for about 10% of the average daily iron intake, but it is well absorbed (about 25%). Key: Heme Nonheme iron accounts for the remaining 90%, but it is less well absorbed (about 17%). Nonheme All of the iron in foods derived from plants is nonheme iron. Stepped Art Fig. 13-3, p. 426

11. Iron • Absorption-inhibiting factors • Phytates • Vegetable proteins • Calcium • Polyphenols • Dietary factors combined • Individual variation in absorption • Health, stage in life cycle, and iron status

12. Iron • Transport • Transferrin • Storage • Ferritin • Hemosiderin • Recycling • Balance • Hepcidin

13. Some losses via sweat, skin, and urine Transferrin carries iron in blood. Some iron delivered to myoglobin of muscle cells Liver (and spleen) dismantles red blood cells, packages iron into transferrin, and stores excess iron in ferritin (and hemosiderin). Bone marrow incorporates iron into hemoglobin of red blood cells and stores excess iron in ferritin (and hemosiderin). Iron-containing hemoglobin in red blood cells carries oxygen. Some losses if bleeding occurs Stepped Art Fig. 13-4, p. 428

14. Iron • Deficiency • Most common nutrient deficiency worldwide • Populations affected in U.S. • Link with being overweight • Vulnerable stages in life • Women in reproductive years • Pregnancy • Infants and young children • Adolescence

15. Iron • Deficiency • Blood losses • Assessment of deficiency • Deficiency develops in stages • Iron stores diminish – serum ferritin • Decrease in transport iron – transferrin • Iron deficiency – hemoglobin and hematocrit values

16. Iron • Iron deficiency and anemia • Deficiency – depleted iron stores without regard to degree of depletion • Anemia – severe depletion of iron stores • Low hemoglobin concentrations • Results

17. Normal and Anemic Blood Cells

18. Iron • Deficiency and behavior • Energy metabolism is impaired • Neurotransmitter synthesis is altered • Reduces work capacity and mental productivity • Motivational problems • Pica • Craving and consumption of nonfood substances

19. Iron • Toxicity • Hereditary hemochromatosis • Most common genetic disorder in U.S. • Hemosiderosis • Signs and symptoms • Transferrin saturation & serum ferritin • Characteristics of condition • Treatment

20. Iron • Heart disease • Excess iron • Free radicals • Cancer • Free-radical damage • Iron poisoning • Symptoms of toxicity • UL

21. Iron • Recommendations and sources • Select iron-rich foods • Natural – meats, fish, poultry, legumes, eggs • Enriched – flour and grain products • RDAs • Vegetarians • Women • Maximizing absorption

22. Iron in Selected Foods

23. Iron • Contamination & supplementation • Iron cookware • Iron content of foods • Supplements • Groups that may need supplements • Enhancing absorption • Vitamin C • Physician prescription

24. Zinc • Roles in body • Gene expression • Cell membranes • Immune function • Growth & development • Synthesis, storage, and release of insulin • Blood clotting • Thyroid hormone function • Behavior & learning performance • Visual pigment • Taste perception • Sperm production

25. Zinc • Absorption • Rate varies depending on zinc status • Dietary factors • Recycling • Small intestine • Two doses of zinc • Enteropancreatic circulation • Zinc losses

26. Enteropancreatic Circulation of Zinc

27. Zinc in food If the body does not need zinc Zinc is not absorbed and is excreted in shed intestinal cells instead. Thus, zinc absorption is reduced when the body does not need zinc. Mucosal cells in the intestine store excess zinc in metallothionein. The pancreas uses zinc to make digestive enzymes and secretes them into the intestine. If the body needs zinc Metallothionein releases zinc to albumin and transferrin for transport to the rest of the body. Stepped Art Fig. 13-7, p. 435

28. Zinc • Transport • In the blood • Albumin • Transferrin • Iron and zinc interactions • Zinc and copper interactions

29. Zinc • Deficiency • Vulnerable groups • Rich sources of zinc • Dietary components that inhibit zinc absorption • Effects of zinc deficiency • Growth retardation • Impaired immune response • Damage to central nervous system

30. Zinc • Toxicity • Symptoms • Interference with copper metabolism • Sources • Protein-rich foods • Recommendations • Supplementation • Treatment of childhood infections

31. Zinc in Selected Foods

32. Iodine • GI tract converts iodine to iodide • Iodine – in food • Iodide – in body • Roles in the body • Part of thyroid hormones • Body temperature, metabolic rate, reproduction, growth, blood cell production, nerve and muscle function, etc.

33. Iodine • Deficiency • Thyroid hormone production declines • Greater secretion of thyroid-stimulating hormone (TSH) • Goiter • Most common cause of preventable mental retardation and brain damage • Cretinism • Iodized salt

34. Iodine • Toxicity • Interferes with thyroid function • Enlarges thyroid gland • Goiter in an infant • UL • Recommendations • Sources • Processed foods

35. Selenium • Substitute for sulfur in some amino acids • Methionine, cysteine, and cystine • Roles in body • Antioxidant • Part of proteins • Glutathione peroxidase • Conversion of thyroid hormone to active form

36. Selenium • Deficiency • Heart disease • Cancer • May be protective factor • Foods vs. supplements • Toxicity • UL • Effects

37. Selenium • Sources • Found in soil • Meats, milk, and eggs • Brazil nuts • Recommendations • RDA • Based on glutathione peroxidase activity

38. Copper • Transport and balance depend on a system of proteins • Roles in body • Constituent of enzymes • Reactions that consume oxygen or oxygen radicals • Iron metabolism • Defense against oxidative damage • Other roles

39. Copper • Deficiency • Cardiovascular disease • Toxicity • Excessive intakes • Foods vs. supplements • Genetic disorders • Menkes disease • Wilson’s disease

40. Copper • Sources • Legumes, whole grains, nuts, shellfish, seeds • Copper plumbing • More than half of copper from foods is absorbed • Route of elimination • Bile

41. Manganese • Body locations • Bones • Metabolically active organs • Roles in body • Cofactor for enzymes that facilitate metabolism • Bone formation • Conversion of pyruvate to a TCA cycle compound

42. Manganese • Deficiency • Requirements are low • Factors limiting manganese absorption • Toxicity • Environmental contaminate • UL • Recommendations and sources • Grain products

43. Fluoride • Found in bones & teeth • Fluorapatite • Dental decay • Sources • Drinking water • Tea and fish • Toxicity • Fluorosis

44. Chromium • Roles in the body • Participates in carbohydrate and lipid metabolism • Helps maintain glucose homeostasis • Diabetes-like condition • Sources • Refined foods • Supplements

45. Molybdenum • Working part of several metalloenzymes • Dietary deficiencies are unknown • Sources • Legumes, breads, grain products, leafy green vegetables, milk, and liver • Toxicity is rare • UL • Characteristics

46. Other Trace Minerals • Research is difficult • Small quantities • Human deficiencies are unknown • Nickel • Silicon • Vanadium • Cobalt • Boron

47. Contaminant Minerals • Impair body’s growth, work capacity, and general health • Heavy metals • Lead • Indestructible • Displaces other minerals • Mercury • Cadmium

48. Closing Thoughts on the Nutrients • Look at nutrients as a whole • Work cooperatively with one another • Actions are most often interactions • Most foods deliver multiple nutrients • Needs are based on the support of optimal health • Nutrients are being examined in context of whole diet

49. Highlight 13 Phytochemicals and Functional Foods

50. Phytochemicals • Found in plant-derived foods • Have biological activity in the body • Physiological effects • Suppression of diseases • Adverse effects if consumed in excess